1. Field of the Invention
The present invention relates generally to Power over Ethernet (PoE) and, more particularly, to a system and method for operating system power management in a computing device for PoE.
2. Introduction
The IEEE 802.3af and 802.3at PoE specifications provide a framework for delivery of power from power sourcing equipment (PSE) to a powered device (PD) over Ethernet cabling. Various types of PDs exist, including voice over IP (VoIP) phones, wireless LAN access points, Bluetooth access points, network cameras, computing devices, etc.
In the PoE process, a valid device detection is first performed. This detection process identifies whether or not it is connected to a valid device to ensure that power is not applied to non-PoE capable devices. After a valid PD is discovered, the PSE can optionally perform a power classification. The completion of this power classification process enables the PSE to manage the power that is delivered to the various PDs connected to the PSE.
Managing PDs is one of the tasks of the PSE. In general, a PSE is designed to provide stable output power to a PD. One example of such a PD is a computing device (e.g., laptop computer or other software controlled device), which can have varying power requirements depending on the operation of its internal components. These internal components need not be uniform and can vary greatly between devices depending on the manufacturer and component suppliers. Moreover, power usage can be highly dependent on the application(s) running on the computing device as well as devices attached to the computing devices.
In one operating state, the computing device can be in a relatively idle state or performing simple tasks such as word processing. In another operating state, the computing device can be performing a variety of simultaneous tasks such as video encoding, disc burning, game playing, and even powering other USB devices. As would be appreciated, transitions between the various operating states can be rapid and continual as the usage requirements of the computing device change in accordance with the directives of the user. What is needed therefore is a mechanism for managing the power delivered to such PDs based on various state information available for such devices.